PLC5 dlen error codes

OK guys I work for a fairly large well known company we dont make cars but do make engines.
My new role has me now using some AB PLC5 gear and had a problem lastnight where a BTR -BTW runs were showing dlen -9 which I believe is an error code but I can not find any refference to the error codes anywhere .
Does anyone know what this code means ??
Me and my shift partner have handed this over to our morning shift but after a re-download of the PLC program no success a new card fitted same issue and we have a test rig so tried the new card in there works fine with exactly the same program running so any chance someone could point me to where these error codes are kept please

click the BTW or BTR on your screen - then hit the F1 key for Help ...

scroll down (way down) for a link to the error codes ...

-9 looks like a Block Transfer timeout error ...

you can find more details in the PLC-5 Instruction Set Reference Manual at this link:

http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1785-rm001_-en-p.pdf

Block Transfers - including the error codes - are in Chapter 15 ...

welcome to the forum ...

From recollection I think in a running system the DLen will be in your case would be 9 when the module goes to fault it will show a minus in your case a -9
I believe I have always been able to reset the module by recycling the power that supplies the module.

I also have only seen this on a Flex I/O module that is attached as Remote I/O to a PLC5